DISCUSSION AND CONCLUSION

The advantages of ISL uranium mining, where a uranium deposit is amenable, has contributed to its popularity and use worldwide. In general, the advantages outweigh the disadvantages, but there are some historic examples of technological or economic failure of the mining method and of unintended negative environmental effects and legacies. Hence, with any mining project, a careful and sufficiently robust feasibility study and risk analysis should be undertaken before a project commences. The issue of active versus passive subsurface remediation of groundwater on closure should be carefully considered and justified, although the choice may currently be limited to active remediation by regulation in some jurisdictions. Demonstration of the effectiveness of the containment of mining solutions during operations, and the achieving of groundwater quality goals on closure, should also feature in any project. Consideration should be given to contingency plans during operations and closure to allow additional intervention if the migration of mining solutions or impacted groundwaters could cause site specific groundwater protection and closure goals to be breached.

ISL uranium production can be expected to account for almost 50% of world production during the next few years [1]. In the longer term, however, this percentage may decrease, as more high-grade deposits in Canada and additional low-high-grade heap leach deposits in Africa (and elsewhere) could be brought into production. Nevertheless, the IAEA report [1] suggests that ISL will continue to be a very significant component of world uranium production for the foreseeable future.

The same report concludes: “[I]n summary, safety, societal aspects, environmental and radiation protection and successful progressive and final rehabilitation will continue to be vital to ongoing uranium mining globally, to ISL as much as more ‘conventional’ mining.”

ACKNOWLEDGEMENTS

The IAEA’s “In Situ Leach Uranium Mining — An Overview of Operations” report [1] was the outcome of two IAEA Technical Meeting and three associated consultants’ meetings, 2010–

2013. The responsible IAEA Technical Officers for that publication are P. Woods and J. Slezak, and the other contributing authors are V. Benes (Czech Republic), O. Gorbatenko (Kazakhstan), B. Jones (Australia), H. Märten (Germany/Australia), T. Pool (USA) and I. Solodov (Russian Federation) [24]. M. Potot–Tarmann of the IAEA greatly assisted with checking and formatting the report. Only selected excerpts are highlighted here.

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1396, IAEA, Vienna (2004).

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Technical, Environmental and Economic Aspects, IAEA–TECDOC–492, Vienna, Austria (1989).

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[13] COMMONWEALTH OF AUSTRALIA, Australia’s in situ recovery uranium mining best practice guide, Canberra, Australia (2010).

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[15] BENEŠ, V., “Acid ISL of uranium in Czech Republic”, The Uranium Mining Remediation Exchange Group (UMREG) Selected Papers 1995–2007, IAEA, Vienna, STI/PUB/1524 (2012) 238–246.

[16] SEDLÁKOVÁ, V., KAŠPAR, L., TÝKAL, T., “Experiences with new neutralization technologies for remediation after ISL mining of uranium in Stráž Pod Ralskem”, Proc.

ASME 2013 15th Int. Conf. Environ. Remediation and Radioactive Waste Management ICEM2013, Brussels, 2013, Am. Soc. Mech. Engrs (2013).

[17] VOKÁL, V., MUŽÁK, J., EKERT, V., “Remediation of uranium In-Situ Leaching area at Stráž Pod Ralskem, Czech Republic”, Proc. ASME 2013 15th Int. Conf. Environ.

Remediation and Radioactive Waste Management ICEM2013, Brussels, 2013, Am. Soc.

Mech. Engrs (2013).

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[19] FIEDLER, J, SLEZÁK, J., “Experience with the Coexistence of Classical Deep Mining and In-Situ Leaching of Uranium in Northern Bohemia”, Uranium In Situ Leaching, IAEA–TECDOC–720, IAEA, Vienna (1993) 115–128.

[20] TAYLOR, G., FARRINGTON, V., WOODS, P., RING, R., MALLOY, R. Review of Environmental Impacts of the Acid In-Situ Leach Uranium Mining Process, CSIRO Land and Water for South Australian Environment Protection Authority, Adelaide, (2004).

[21] KALKA, H., MÄRTEN, H., WOODS, P. “ISR Mine Closure Concepts”, Proc.

Internationalen Bergbausymposiums WISSYM_2011, Wismut Symposium:

Sustainability and Long Term Aspects of the Remediation of U Mine and Milling Sites, Ronneburg, Germany, 2011 (2011) 201–215.

[22] YAZIKOV, V.G., ZABAZNOV, V.U., “Experience with Restoration of Ore-Bearing Aquifers after In Situ Leach Uranium Mining”, The Uranium Production Cycle and the Environment, IAEA C&S Papers Series No. 10/P, IAEA, Vienna (2002) 396–402.

[23] URS AUSTRALIA PTY LTD, Beverley North Project Mining Lease Proposal and Draft Public Environment Report. Prepared for Heathgate Resources Pty Ltd, Adelaide (2010).

[24] WOODS, P., POOL, T., BENEŠ, V., GORBATENKO, O, JONES, B., MÄRTEN, H., SOLODOV, I., SLEZAK, J. International overview of ISL uranium mining operations.

IAEA–CN–216 Abstract 031, IAEA International Symposium on Uranium Raw Material for the Nuclear Fuel Cycle: Exploration, Mining, Production, Supply and Demand, Economics and Environmental Issues Vienna, Austria, 23 to 27 June 2014, Abstr. Vol. (2014) 189.

REMEDIATION OF FORMER URANIUM IN SITU LEACHING AREA AT STRAZ POD RALSKEM

HAMR NA JEZERE, CZECH REPUBLIC²⁴

A large scale development in exploration and production of uranium ores in the Czech Republic was done in the second half of the 20th century. Many uranium deposits were discovered in the territory of the Czech Republic. Over a period of 50 years approx. 110 000 tonnes of uranium in concentrate were produced. Different mining methods were developed and used.

One of the most considerable deposits in the Czech Republic is the site Hamr na Jezere–Straz pod Ralskem where both mining methods (underground mining and acidic in situ leaching) were used. The extensive production of uranium led to widespread environmental impacts and contamination of ground waters. Over the period of ‘chemical’ leaching of uranium (approximately 32 years), a total of more than 4 Mt of sulphuric acid and other chemicals have been injected into the ground. Most of the products (approx. 99.5%) of the acids reactions with the rocks are located in the Cenomanian aquifer. The contamination of Cenomanian aquifer covers the area larger than 27 km². The influenced volume of groundwater is more than 380 Mm³. The total amount of dissolved SO42- is about 3.6 Mt. Approximately 0.5 % of the contamination is located in the Turonian aquifer.

After 1990 a large scale environmental program was established and the Czech government decided to liquidate the ISL Mine and start the remediation in 1996. The remediation consists of contaminated groundwater pumping, removing of the contaminants and discharging or reinjection of treated water. The objectives of the remedial activities are described in following points: to restore the rock environment to a condition guaranteeing continuing usability of Turonian water of Northern Bohemia Cretaceous, to decommission boreholes and surface installations and to incorporate the surface of leaching fields into the ecosystems taking into account regional systems of ecological stability and urban plans. Nowadays four main remedial technological installations for reaching of these aims are used — the “Station for Acid Solutions Liquidation No. One”, the

“Mother liquor reprocessing” station, the “Neutralization and Decontamination Station NDS 6” and the “Neutralization and Decontamination Station NDS 10”. Total capacity of this complex is sufficient to reach the target values of remedial parameters in 2037. The remediation action consists of: pumping of residual solution to the surface, separating uranium from the solution and reprocessing contaminants into commercially usable or ecologically storable products. It is expected that the amount of withdrawn contaminants will vary from 80 000 to 120 000 tonnes per year. Total costs of all remediation activities are expected to be in excess of 1.5 billion EUR.

1. INTRODUCTION

The history of uranium exploitation in the Czech Republic (and in the former Czechoslovakia) dates back more than 60 years. Over the initial period, from 1946 until the beginning of the 1950s, the exploitation was mainly carried out in the reopened mines of the Jachymov mining area. Rapid development of surveying and extracting work was reflected in the large growth of exploitation in other areas of Bohemia and Moravia. This concerned the regions Pribram, Hamr na Jezere–Straz pod Ralskem and Dolni Rozinka, i.e. southern, northern and western Bohemia.

More than 100 000 tonnes of uranium had been extracted from over 800 trial and production shafts since 1946.

Owing to the diversity of the deposits, the uranium exploitation was carried out with the whole spectrum of mining methods available, which were selected as appropriate for the host rock at the given locality. In general terms, there are two basic methods of uranium extraction applied in the Czech Republic:

— Conventional underground mine workings;

— In situ leaching (ISL).

24 Based on the papers “Remediation of consequences of chemical leaching of uranium in Stráž pod Ralskem” and

“Overview of the ISL remediation at Straz pod Ralskem” first presented at the Technical Meeting of the UMREG

2. URANIUM MINING HISTORY AT THE HAMR NA JEZERE–STRAZ POD